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[/] [System09/] [trunk/] [rtl/] [VHDL/] [ps2_keyboard.vhd] - Diff between revs 66 and 99

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Line 1... Line 1... 
---------------------------------------------------------------------------------------
 
--===========================================================================--
 
 
 
--                                                                           --
 
 
 
--  ps2_keyboard.vhd - Synthesizable PS/2 Keyboard Interface                 --
 
 
 
--                                                                           --
 
 
 
--===========================================================================--
 
--
 
--
 
-- Author: John Clayton
 
--  File name      : ps2_keyboard.vhd
 
-- Date  : April 30, 2001
 
 
 
-- Update: 4/30/01 copied this file from lcd_2.v (pared down).
 
 
 
-- Update: 5/24/01 changed the first module from "ps2_keyboard_receiver"
 
 
 
--                 to "ps2_keyboard_interface"
 
 
 
-- Update: 5/29/01 Added input synchronizing flip-flops.  Changed state
 
 
 
--                 encoding (m1) for good operation after part config.
 
 
 
-- Update: 5/31/01 Added low drive strength and slow transitions to ps2_clk
 
 
 
--                 and ps2_data in the constraints file.  Added the signal
 
 
 
--                 "tx_shifting_done" as distinguished from "rx_shifting_done."
 
 
 
--                 Debugged the transmitter portion in the lab.
 
 
 
-- Update: 6/01/01 Added horizontal tab to the ascii output.
 
 
 
-- Update: 6/01/01 Added parameter TRAP_SHIFT_KEYS.
 
 
 
-- Update: 6/05/01 Debugged the "debounce" timer functionality.
 
 
 
--                 Used 60usec timer as a "watchdog" timeout during
 
 
 
--                 receive from the keyboard.  This means that a keyboard
 
 
 
--                 can now be "hot plugged" into the interface, without
 
 
 
--                 messing up the bit_count, since the bit_count is reset
 
 
 
--                 to zero during periods of inactivity anyway.  This was
 
 
 
--                 difficult to debug.  I ended up using the logic analyzer,
 
 
 
--                 and had to scratch my head quite a bit.
 
 
 
-- Update: 6/06/01 Removed extra comments before the input synchronizing
 
 
 
--                 flip-flops.  Used the correct parameter to size the
 
 
 
--                 5usec_timer_count.  Changed the name of this file from
 
 
 
--                 ps2.v to ps2_keyboard.v
 
 
 
-- Update: 6/06/01 Removed "&& q[7:0]" in output_strobe logic.  Removed extra
 
 
 
--                 commented out "else" condition in the shift register and
 
 
 
--                 bit counter.
 
 
 
-- Update: 6/07/01 Changed default values for 60usec timer parameters so that
 
 
 
--                 they correspond to 60usec for a 49.152MHz clock.
 
 
 
--
 
--
 
--      Converted to VHDL: 10 February 2004 - John Kent
 
--  Purpose        : Implements a PS/2 Keyboard Interface
 
-- 11 Sept 04   added ctrl key 
 
 
--              changed undefined key codes to x"ff"
 
 
 
--              reversed clock polarity
 
 
 
--
 
--
 
-- 18th Oct 04  added ctrl keys to ASCII ROM
 
--  Dependencies   : ieee.std_logic_1164
 
--              added CAPS Lock toggle.
 
--                   ieee.std_logic_unsigned
 
 
 
--                   ieee.std_logic_arith
 
 
 
--                   ieee.numeric_std
 
 
 
--                   unisim.vcomponents
 
--
 
--
 
-- 6th Feb 2007 Added Generic Clock parameter
 
--  Author         : Original Verilog version by John Clayton
 
 
 
--                   Converted to VHDL by John E. Kent
 
 
 
--
 
 
 
--  Email          : dilbert57@opencores.org      
 
 
--
 
 
 
--  Web            : http://opencores.org/project,system09
 
--
 
--
 
---------------------------------------------------------------------------------------
 
 
 
-- Description:
 
-- Description:
 
---------------------------------------------------------------------------------------
 
--
 
-- This is a state-machine driven serial-to-parallel and parallel-to-serial
 
-- This is a state-machine driven serial-to-parallel and parallel-to-serial
 
-- interface to the ps2 style keyboard interface.  The details of the operation
 
-- interface to the ps2 style keyboard interface.  The details of the operation
 
-- of the keyboard interface were obtained from the following website:
 
-- of the keyboard interface were obtained from the following website:
 
--
 
--
 
--   http:--www.beyondlogic.org/keyboard/keybrd.htm
 
--   http://www.beyondlogic.org/keyboard/keybrd.htm
 
--
 
--
 
-- Some aspects of the keyboard interface are not implemented (e.g, parity
 
-- Some aspects of the keyboard interface are not implemented (e.g, parity
 
-- checking for the receive side, and recognition of the various commands
 
-- checking for the receive side, and recognition of the various commands
 
-- which the keyboard sends out, such as "power on selt test passed," "Error"
 
-- which the keyboard sends out, such as "power on selt test passed," "Error"
 
-- and "Resend.")  However, if the user wishes to recognize these reply
 
-- and "Resend.")  However, if the user wishes to recognize these reply
Line 107... Line 86... 
-- lines, there is some bouncing around which occurs
 
-- lines, there is some bouncing around which occurs
 
--
 
--
 
-- A parameter TRAP_SHIFT_KEYS allows the user to eliminate shift keypresses
 
-- A parameter TRAP_SHIFT_KEYS allows the user to eliminate shift keypresses
 
-- from producing scan codes (along with their "undefined" ASCII equivalents)
 
-- from producing scan codes (along with their "undefined" ASCII equivalents)
 
-- at the output of the interface.  If TRAP_SHIFT_KEYS is non-zero, the shift
 
-- at the output of the interface.  If TRAP_SHIFT_KEYS is non-zero, the shift
 
-- key status will only be reported by rx_shift_key_on.  No ascii or scan
 
-- key status will only be reported by rx_shift_on.  No ascii or scan
 
-- codes will be reported for the shift keys.  This is useful for those who
 
-- codes will be reported for the shift keys.  This is useful for those who
 
-- wish to use the ASCII data stream, and who don't want to have to "filter
 
-- wish to use the ASCII data stream, and who don't want to have to "filter
 
-- out" the shift key codes.
 
-- out" the shift key codes.
 
--
 
--
 
 
 
--  Copyright (C) 2001 - 2010 John Clayton and John Kent
 
 
 
--
 
 
 
--  This program is free software: you can redistribute it and/or modify
 
 
 
--  it under the terms of the GNU General Public License as published by
 
 
 
--  the Free Software Foundation, either version 3 of the License, or
 
 
 
--  (at your option) any later version.
 
 
 
--
 
 
 
--  This program is distributed in the hope that it will be useful,
 
 
 
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
 
 
 
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
 
 
--  GNU General Public License for more details.
 
 
 
--
 
 
 
--  You should have received a copy of the GNU General Public License
 
 
 
--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
 
--
 
 
 
--===========================================================================--
 
 
 
--                                                                           --
 
 
 
--                              Revision  History                            --
 
 
 
--                                                                           --
 
 
 
--===========================================================================--
 
 
 
--
 
 
 
-- Author: John Clayton
 
 
 
-- 2001-04-30 copied this file from lcd_2.v (pared down).
 
 
 
-- 2001-05-24 changed the first module from "ps2_keyboard_receiver"
 
 
 
--            to "ps2_keyboard_interface"
 
 
 
-- 2001-05-29 Added input synchronizing flip-flops.  Changed state
 
 
 
--            encoding (m1) for good operation after part config.
 
 
 
-- 2001-05-31 Added low drive strength and slow transitions to ps2_clk
 
 
 
--            and ps2_data in the constraints file.  Added the signal
 
 
 
--            "tx_shifting_done" as distinguished from "rx_shifting_done."
 
 
 
--            Debugged the transmitter portion in the lab.
 
 
 
-- 2001-06-01 Added horizontal tab to the ascii output.
 
 
 
-- 2001-06-01 Added parameter TRAP_SHIFT_KEYS.
 
 
 
-- 2001-06-05 Debugged the "debounce" timer functionality.
 
 
 
--            Used 60usec timer as a "watchdog" timeout during
 
 
 
--            receive from the keyboard.  This means that a keyboard
 
 
 
--            can now be "hot plugged" into the interface, without
 
 
 
--            messing up the bit_count, since the bit_count is reset
 
 
 
--            to zero during periods of inactivity anyway.  This was
 
 
 
--            difficult to debug.  I ended up using the logic analyzer,
 
 
 
--            and had to scratch my head quite a bit.
 
 
 
-- 2001-06-06 Removed extra comments before the input synchronizing
 
 
 
--            flip-flops.  Used the correct parameter to size the
 
 
 
--            5usec_timer_count.  Changed the name of this file from
 
 
 
--            ps2.v to ps2_keyboard.v
 
 
 
-- 2001-06/06 Removed "&& q[7:0]" in output_strobe logic.  Removed extra
 
 
 
--            commented out "else" condition in the shift register and
 
 
 
--            bit counter.
 
 
 
-- 2001-06-07 Changed default values for 60usec timer parameters so that
 
 
 
--            they correspond to 60usec for a 49.152MHz clock.
 
 
 
--
 
 
 
-- Author: John Kent
 
 
 
--      2001-02-10 Converted to VHDL
 
 
 
-- 2004-09-11 Added ctrl key 
 
 
--            Changed undefined key codes to x"ff"
 
 
 
--            Reversed clock polarity
 
 
 
-- 2004-10-18 Added ctrl keys to ASCII ROM
 
 
 
--            Added CAPS Lock toggle.
 
 
 
-- 2007-02-06 Added Generic Clock parameter
 
 
 
-- 2010-05-31 Revised header, added GPL
 
 
 
-- 2010-06-17 Change some signal names for consistancy
 
 
 
--
 
 
 
--
 
--
 
--
 
---------------------------------------------------------------------------------------
 
---------------------------------------------------------------------------------------
 
 
 
 
 
library ieee;
 
library ieee;
 
   use ieee.std_logic_1164.all;
 
   use ieee.std_logic_1164.all;
 
   use IEEE.STD_LOGIC_ARITH.ALL;
 
   use ieee.std_logic_arith.all;
 
   use IEEE.STD_LOGIC_UNSIGNED.ALL;
 
   use ieee.std_logic_unsigned.all;
 
   use ieee.numeric_std.all;
 
   use ieee.numeric_std.all;
 
 
 
library unisim;
 
 
 
   use unisim.vcomponents.all;
 
 
 
 
 
entity ps2_keyboard_interface is
 
entity ps2_keyboard is
 
  generic (
 
  generic (
 
  Frequency_MHz   : integer
 
  CLK_FREQ_MHZ   : integer
 
  );
 
  );
 
 
 
 
 
  port(
 
  port(
 
  clk             : in    std_logic;
 
  clk             : in    std_logic;
 
  reset           : in    std_logic;
 
  reset           : in    std_logic;
 
  ps2_clk         : inout std_logic;
 
  rx_data         : out   std_logic_vector(7 downto 0);
 
  ps2_data        : inout std_logic;
 
  rx_read         : in    std_logic;
 
 
 
  rx_data_ready   : out   std_logic;
 
  rx_extended     : out   std_logic;
 
  rx_extended     : out   std_logic;
 
  rx_released     : out   std_logic;
 
  rx_released     : out   std_logic;
 
  rx_shift_key_on : out   std_logic;
 
  rx_shift_on     : out   std_logic;
 
--  rx_scan_code    : out   std_logic_vector(7 downto 0);
 
 
 
  rx_ascii        : out   std_logic_vector(7 downto 0);
 
 
 
  rx_data_ready   : out   std_logic;       -- rx_read_o
 
 
 
  rx_read         : in    std_logic;       -- rx_read_ack_i
 
 
 
  tx_data         : in    std_logic_vector(7 downto 0);
 
  tx_data         : in    std_logic_vector(7 downto 0);
 
  tx_write        : in    std_logic;
 
  tx_write        : in    std_logic;
 
  tx_write_ack    : out   std_logic;
 
  tx_data_empty   : out   std_logic;
 
  tx_error_no_keyboard_ack      : out  std_logic
 
  tx_error            : out   std_logic;
 
 
 
  ps2_clk         : inout std_logic;
 
 
 
  ps2_data        : inout std_logic
 
  );
 
  );
 
end ps2_keyboard_interface;
 
end ps2_keyboard;
 
 
 
 
 
-------------------------------------------------------------------------------
 
-------------------------------------------------------------------------------
 
-- Architecture for ps2 keyboard interface
 
-- Architecture for ps2 keyboard interface
 
-------------------------------------------------------------------------------
 
-------------------------------------------------------------------------------
 
architecture rtl of ps2_keyboard_interface is
 
architecture rtl of ps2_keyboard is
 
  -----------------------------------------------------------------------------
 
  -----------------------------------------------------------------------------
 
 
 
 
 
 
 
 
 
constant TOTAL_BITS   : integer := 11;
 
constant TOTAL_BITS   : integer := 11;
 
constant EXTEND_CODE  : integer := 16#E0#;
 
constant EXTEND_CODE  : integer := 16#E0#;
Line 183... Line 226... 
--constant TIMER_60USEC_BITS_PP  : integer := 11;   -- Number of bits needed for timer
 
--constant TIMER_60USEC_BITS_PP  : integer := 11;   -- Number of bits needed for timer
 
--constant TIMER_5USEC_VALUE_PP  : integer := 125;  -- Number of sys_clks for debounce
 
--constant TIMER_5USEC_VALUE_PP  : integer := 125;  -- Number of sys_clks for debounce
 
--constant TIMER_5USEC_BITS_PP   : integer := 7;    -- Number of bits needed for timer
 
--constant TIMER_5USEC_BITS_PP   : integer := 7;    -- Number of bits needed for timer
 
 
 
 
 
-- Values for  generic Clock up to 50 MHz
 
-- Values for  generic Clock up to 50 MHz
 
constant TIMER_60USEC_VALUE_PP : integer := Frequency_MHz * 60; -- Number of sys_clks for 60usec.
 
constant TIMER_60USEC_VALUE_PP : integer := CLK_FREQ_MHZ * 60;  -- Number of sys_clks for 60usec.
 
constant TIMER_60USEC_BITS_PP  : integer := 12;                 -- Number of bits needed for timer
 
constant TIMER_60USEC_BITS_PP  : integer := 12;                 -- Number of bits needed for timer
 
constant TIMER_5USEC_VALUE_PP  : integer := Frequency_MHz * 5;  -- Number of sys_clks for debounce
 
constant TIMER_5USEC_VALUE_PP  : integer := CLK_FREQ_MHZ * 5;   -- Number of sys_clks for debounce
 
constant TIMER_5USEC_BITS_PP   : integer := 8;                  -- Number of bits needed for timer
 
constant TIMER_5USEC_BITS_PP   : integer := 8;                  -- Number of bits needed for timer
 
 
 
 
 
constant TRAP_SHIFT_KEYS_PP    : integer := 1;   -- Default: No shift key trap.
 
constant TRAP_SHIFT_KEYS_PP    : integer := 1;   -- Default: No shift key trap.
 
 
 
 
 
-- State encodings, provided as constants
 
-- State encodings, provided as constants
Line 207... Line 250... 
 
 
 
 
type m1_type is ( m1_rx_clk_h, m1_rx_clk_l,
 
type m1_type is ( m1_rx_clk_h, m1_rx_clk_l,
 
                  m1_tx_wait_clk_h, m1_tx_force_clk_l,
 
                  m1_tx_wait_clk_h, m1_tx_force_clk_l,
 
                                                m1_tx_clk_h, m1_tx_clk_l,
 
                                                m1_tx_clk_h, m1_tx_clk_l,
 
                                                m1_tx_wait_keyboard_ack, m1_tx_done_recovery,
 
                                                m1_tx_wait_keyboard_ack, m1_tx_done_recovery,
 
                                                m1_tx_error_no_keyboard_ack, m1_tx_rising_edge_marker,
 
                                                m1_tx_error, m1_tx_rising_edge_marker,
 
                                                m1_tx_first_wait_clk_h, m1_tx_first_wait_clk_l, m1_tx_reset_timer,
 
                                                m1_tx_first_wait_clk_h, m1_tx_first_wait_clk_l, m1_tx_reset_timer,
 
                  m1_rx_falling_edge_marker, m1_rx_rising_edge_marker );
 
                  m1_rx_falling_edge_marker, m1_rx_rising_edge_marker );
 
 
 
 
 
-- Internal signal declarations
 
-- Internal signal declarations
 
signal timer_60usec_done  : std_logic;
 
signal timer_60usec_done  : std_logic;
Line 252... Line 295... 
signal hold_released      : std_logic;  -- Holds prior value, cleared at rx_output_strobe
 
signal hold_released      : std_logic;  -- Holds prior value, cleared at rx_output_strobe
 
signal ps2_clk_s          : std_logic;  -- Synchronous version of this input
 
signal ps2_clk_s          : std_logic;  -- Synchronous version of this input
 
signal ps2_data_s         : std_logic;  -- Synchronous version of this input
 
signal ps2_data_s         : std_logic;  -- Synchronous version of this input
 
signal ps2_clk_hi_z       : std_logic;  -- Without keyboard, high Z equals 1 due to pullups.
 
signal ps2_clk_hi_z       : std_logic;  -- Without keyboard, high Z equals 1 due to pullups.
 
signal ps2_data_hi_z      : std_logic;  -- Without keyboard, high Z equals 1 due to pullups.
 
signal ps2_data_hi_z      : std_logic;  -- Without keyboard, high Z equals 1 due to pullups.
 
signal tx_write_ack_o     : std_logic;
 
signal tx_data_empty_o    : std_logic;
 
 
 
 
 
--
 
--
 
-- key lookup table
 
-- key lookup table
 
--
 
--
 
component keymap_rom
 
component keymap_rom
Line 264... Line 307... 
       clk   : in  std_logic;
 
       clk   : in  std_logic;
 
                 rst   : in  std_logic;
 
                 rst   : in  std_logic;
 
                 cs    : in  std_logic;
 
                 cs    : in  std_logic;
 
                 rw    : in  std_logic;
 
                 rw    : in  std_logic;
 
       addr  : in  std_logic_vector (8 downto 0);
 
       addr  : in  std_logic_vector (8 downto 0);
 
       rdata : out std_logic_vector (7 downto 0);
 
    data_in  : in  std_logic_vector (7 downto 0);
 
       wdata : in  std_logic_vector (7 downto 0)
 
    data_out : out std_logic_vector (7 downto 0)
 
    );
 
    );
 
end component;
 
end component;
 
 
 
 
 
begin
 
begin
 
 
 
 
Line 278... Line 321... 
          clk  => clk,
 
          clk  => clk,
 
          rst  => reset,
 
          rst  => reset,
 
          cs   => '1',
 
          cs   => '1',
 
          rw   => '1',
 
          rw   => '1',
 
          addr => shift_key_plus_code,
 
          addr => shift_key_plus_code,
 
          rdata => ascii,
 
          data_in  => "00000000",
 
          wdata => "00000000"
 
          data_out => ascii
 
          );
 
          );
 
 
 
 
 
----------------------------------------------------------------------------
 
----------------------------------------------------------------------------
 
-- Module code
 
-- Module code
 
-- assign ps2_clk = ps2_clk_hi_z?1'bZ:1'b0;
 
-- assign ps2_clk = ps2_clk_hi_z?1'bZ:1'b0;
 
-- assign ps2_data = ps2_data_hi_z?1'bZ:1'b0;
 
-- assign ps2_data = ps2_data_hi_z?1'bZ:1'b0;
 
--
 
--
 
ps2_direction : process( ps2_clk_hi_z, ps2_data_hi_z )
 
ps2_direction : process( ps2_clk_hi_z, ps2_data_hi_z )
 
begin
 
begin
 
 
 
 
 
  if( ps2_clk_hi_z = '1' ) then
 
  if( ps2_clk_hi_z = '1' ) then
 
     ps2_clk <= 'Z';
 
     ps2_clk <= 'Z';
 
  else
 
  else
 
     ps2_clk <= '0';
 
     ps2_clk <= '0';
 
  end if;
 
  end if;
 
 
 
 
 
  if( ps2_data_hi_z = '1' ) then
 
  if( ps2_data_hi_z = '1' ) then
 
     ps2_data <= 'Z';
 
     ps2_data <= 'Z';
 
  else
 
  else
 
     ps2_data <= '0';
 
     ps2_data <= '0';
 
  end if;
 
  end if;
 
 
 
 
 
end process;
 
end process;
 
 
 
 
 
-- Input "synchronizing" logic -- synchronizes the inputs to the state
 
-- Input "synchronizing" logic -- synchronizes the inputs to the state
 
-- machine clock, thus avoiding errors related to
 
-- machine clock, thus avoiding errors related to
 
-- spurious state machine transitions.
 
-- spurious state machine transitions.
Line 332... Line 378... 
                                                                  timer_60usec_done, timer_5usec_done )
 
                                                                  timer_60usec_done, timer_5usec_done )
 
begin
 
begin
 
  -- Output signals default to this value, unless changed in a state condition.
 
  -- Output signals default to this value, unless changed in a state condition.
 
  ps2_clk_hi_z             <= '1';
 
  ps2_clk_hi_z             <= '1';
 
  ps2_data_hi_z            <= '1';
 
  ps2_data_hi_z            <= '1';
 
  tx_error_no_keyboard_ack <= '0';
 
  tx_error                 <= '0';
 
  enable_timer_60usec      <= '0';
 
  enable_timer_60usec      <= '0';
 
  enable_timer_5usec       <= '0';
 
  enable_timer_5usec       <= '0';
 
 
 
 
 
  case (m1_state) is
 
  case (m1_state) is
 
  when m1_rx_clk_h =>
 
  when m1_rx_clk_h =>
Line 433... Line 479... 
                     m1_next_state <= m1_tx_clk_l;
 
                     m1_next_state <= m1_tx_clk_l;
 
        end     if;
 
        end     if;
 
 
 
 
 
  when m1_tx_wait_keyboard_ack =>
 
  when m1_tx_wait_keyboard_ack =>
 
        if (ps2_clk_s = '0') and (ps2_data_s = '1') then
 
        if (ps2_clk_s = '0') and (ps2_data_s = '1') then
 
           m1_next_state <= m1_tx_error_no_keyboard_ack;
 
           m1_next_state <= m1_tx_error;
 
        elsif (ps2_clk_s = '0') and (ps2_data_s = '0') then
 
        elsif (ps2_clk_s = '0') and (ps2_data_s = '0') then
 
           m1_next_state <= m1_tx_done_recovery;
 
           m1_next_state <= m1_tx_done_recovery;
 
        else
 
        else
 
                     m1_next_state <= m1_tx_wait_keyboard_ack;
 
                     m1_next_state <= m1_tx_wait_keyboard_ack;
 
        end     if;
 
        end     if;
Line 447... Line 493... 
                     m1_next_state <= m1_rx_clk_h;
 
                     m1_next_state <= m1_rx_clk_h;
 
        else
 
        else
 
                     m1_next_state <= m1_tx_done_recovery;
 
                     m1_next_state <= m1_tx_done_recovery;
 
        end     if;
 
        end     if;
 
 
 
 
 
  when m1_tx_error_no_keyboard_ack =>
 
  when m1_tx_error =>
 
        tx_error_no_keyboard_ack <= '1';
 
        tx_error <= '1';
 
        if (ps2_clk_s = '1') and (ps2_data_s ='1') then
 
        if (ps2_clk_s = '1') and (ps2_data_s ='1') then
 
                     m1_next_state <= m1_rx_clk_h;
 
                     m1_next_state <= m1_rx_clk_h;
 
        else
 
        else
 
                     m1_next_state <= m1_tx_error_no_keyboard_ack;
 
                     m1_next_state <= m1_tx_error;
 
        end     if;
 
        end     if;
 
 
 
 
 
  when others =>
 
  when others =>
 
             m1_next_state <= m1_rx_clk_h;
 
             m1_next_state <= m1_rx_clk_h;
 
  end case;
 
  end case;
Line 479... Line 525... 
       bit_count <= bit_count + 1;
 
       bit_count <= bit_count + 1;
 
    end if;
 
    end if;
 
  end if;
 
  end if;
 
end process;
 
end process;
 
 
 
 
 
assign: process( bit_count, tx_write, tx_write_ack_o, m1_state )
 
assign: process( bit_count, tx_write, tx_data_empty_o, m1_state )
 
begin
 
begin
 
  if (bit_count = TOTAL_BITS) then
 
  if (bit_count = TOTAL_BITS) then
 
     rx_shifting_done <= '1';
 
     rx_shifting_done <= '1';
 
  else
 
  else
 
     rx_shifting_done <= '0';
 
     rx_shifting_done <= '0';
Line 497... Line 543... 
 
 
 
 
-- This is the signal which enables loading of the shift register.
 
-- This is the signal which enables loading of the shift register.
 
-- It also indicates "ack" to the device writing to the transmitter.
 
-- It also indicates "ack" to the device writing to the transmitter.
 
  if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or
 
  if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or
 
     ((tx_write = '1') and (m1_state = m1_rx_clk_l)) then
 
     ((tx_write = '1') and (m1_state = m1_rx_clk_l)) then
 
     tx_write_ack_o <= '1';
 
     tx_data_empty_o <= '1';
 
  else
 
  else
 
     tx_write_ack_o <= '0';
 
     tx_data_empty_o <= '0';
 
  end if;
 
  end if;
 
  tx_write_ack <= tx_write_ack_o;
 
  tx_data_empty <= tx_data_empty_o;
 
end process;
 
end process;
 
 
 
 
 
-- This is the ODD parity bit for the transmitted word.
 
-- This is the ODD parity bit for the transmitted word.
 
-- assign tx_parity_bit = ~^tx_data;
 
-- assign tx_parity_bit = ~^tx_data;
 
--
 
--
 
tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor
 
tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor
 
                      tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );
 
                      tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );
 
 
 
 
 
-- This is the shift register
 
-- This is the shift register
 
q_shift : process(clk, tx_write_ack_o, tx_parity_bit, tx_data,
 
q_shift : process(clk, tx_data_empty_o, tx_parity_bit, tx_data,
 
                  m1_state, q, ps2_data_s, rx_shifting_done )
 
                  m1_state, q, ps2_data_s, rx_shifting_done )
 
begin
 
begin
 
  if clk'event and clk='0' then
 
  if clk'event and clk='0' then
 
    if (reset = '1') then
 
    if (reset = '1') then
 
            q <= "00000000000";
 
            q <= "00000000000";
 
    elsif (tx_write_ack_o = '1') then
 
    elsif (tx_data_empty_o = '1') then
 
            q <= "1" & tx_parity_bit & tx_data & "0";
 
            q <= "1" & tx_parity_bit & tx_data & "0";
 
    elsif ( (m1_state = m1_rx_falling_edge_marker)      or
 
    elsif ( (m1_state = m1_rx_falling_edge_marker)      or
 
            (m1_state = m1_tx_rising_edge_marker) ) then
 
            (m1_state = m1_tx_rising_edge_marker) ) then
 
       q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);
 
       q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);
 
    end if;
 
    end if;
Line 633... Line 679... 
    end if;
 
    end if;
 
  end if;
 
  end if;
 
end process;
 
end process;
 
 
 
 
 
shift_key_on <= left_shift_key or right_shift_key;
 
shift_key_on <= left_shift_key or right_shift_key;
 
rx_shift_key_on <= shift_key_on;
 
rx_shift_on <= shift_key_on;
 
 
 
 
 
--
 
--
 
-- Control keys
 
-- Control keys
 
--
 
--
 
ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )
 
ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )
Line 681... Line 727... 
  if clk'event and clk = '0' then
 
  if clk'event and clk = '0' then
 
    if (reset = '1')    then
 
    if (reset = '1')    then
 
      rx_extended <= '0';
 
      rx_extended <= '0';
 
      rx_released <= '0';
 
      rx_released <= '0';
 
--      rx_scan_code <= "00000000";
 
--      rx_scan_code <= "00000000";
 
      rx_ascii <= "00000000";
 
      rx_data <= "00000000";
 
    elsif (rx_output_strobe = '1') then
 
    elsif (rx_output_strobe = '1') then
 
      rx_extended <= hold_extended;
 
      rx_extended <= hold_extended;
 
      rx_released <= hold_released;
 
      rx_released <= hold_released;
 
--      rx_scan_code <= q(8 downto 1);
 
--      rx_scan_code <= q(8 downto 1);
 
    elsif ctrl_key_on = '1' then
 
    elsif ctrl_key_on = '1' then
 
           rx_ascii <= ascii and x"1f";
 
           rx_data <= ascii and x"1f";
 
    else
 
    else
 
      rx_ascii <= ascii;
 
      rx_data <= ascii;
 
    end if;
 
    end if;
 
  end if;
 
  end if;
 
end process;
 
end process;
 
 
 
 
 
-- Store the final rx output data only when all extend and release codes
 
-- Store the final rx output data only when all extend and release codes

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